Introduction extracted from Report 284:

REPORT 284 INTRODUCTION A pilot study using heavy mineral concentrate samples from glaciofluvial sediments was conducted over a broad area of Minnesota by the Minnesota Department of Natural Resources, Division of Minerals, in cooperation with the U.S. Geological Survey, Branch of Geochemistry in Denver, Colorado. The study examined the heavy mineral fraction of eighty glaciofluvial samples collected from a number of geologically distinctive areas of the state. It evolved from a similar eight-sample test study that was completed in the previous year through a contract with the USGS.

The overall goals of the project were to educate DNR staff in heavy mineral investigative techniques that have been developed and refined by the USGS and to begin to develop heavy mineral baseline data for a portion of the state. The specific pilot study objectives were threefold: 1) to determine reliable, cost-effective sampling methods, concentration techniques, and analytical methods to use in future heavy mineral studies; 2) to determine the presence of heavy minerals of economic value, either semi- or precious metals and stones or industrial minerals, in glaciofluvial deposits that are currently being mined for sand and gravel; and 3) to determine the presence of heavy minerals in glacigenic sediments that could be used as indicator minerals in regional heavy mineral surveys or used to complement future geochemical terrain surveys.

This open-file report summarizes the sampling strategy and the methods of sample preparation and analysis for the pilot and test study samples and presents the results in table format.

Introduction extracted from Report 284-1:

REPORT 284-1 INTRODUCTION (First 3 Paragraphs) This report presents an interpretation of the results of a study that analyzed the heavy-mineral content of samples collected in Minnesota northeastern-provenance glaciofluvial sediments. Since it's inception, this study has been a cooperative project between the U.S. Geological Survey, Branch of Geochemistry, Colorado, and the Minnesota Department of Natural Resources, Division of Minerals. The project began with an eight-sample test study to determine whether there was enough geochemical and mineralogical variation in the heavy-mineral content of surficial glaciofluvial sediments to observe differences between samples. Test study results showed substantial variation between samples, which led to an eighty-sample pilot study to evaluate whether this variation would show any anomalous values or geographic distribution patterns that could be related to inferred regional bedrock or glacial geology.

The study area traverses Minnesota from the northeast to the southwest and encompasses an area approximately 60 miles wide by 230 miles long (Fig. 1). This area lies on the southern edge of the Canadian Shield and includes several of Minnesota's Precambrian bedrock terranes. Unique lithologic, tectonic, and structural characteristics of the various terranes create an area with diverse mineral potential. The northeast-southwest orientation of the study area was chosen because it is parallel to the major glacial flow and includes glacigenic sediments with a variety of genetic origins, glacial transport paths, and glacial and fluvial transport distances.

Within the study area the primary sampling strategy was to collect samples from late Figure 1. General location of study area in Minnesota. Wisconsinan northeastern-provenance glaciofluvial sand and gravel deposits; these deposits have been sorted by currents, which removed most of the silt and clay and produced some concentration of heavy minerals. Preference was given to sites where the depth to bedrock was 100 feet or less, because glacigenic sediments in these areas are more likely to reflect regional bedrock. Most samples were collected in gravel pits; with sampling preference given to ice-contact stratified sediments over outwash sediments...

1United State Geological Survey, Geochemical Branch, Denver, Colorado
Please note: Best results in viewing these reports will be obtained by saving the files to a location of your choice and opening with Adobe Reader or Acrobat. Some report information may not display as a result of opening with Acrobat directly from a web browser.

This reports have been scanned in and applied with optical character recognition (OCR) which electronically translates the scanned image printed text into machine-encoded text. This allows users to thensearch the document by keywords in Adobe Reader or Acrobat software.

3. Download GIS data:

The zip file contains data for samples extracted from eighty-eight glaciofluvial samples described in the Minnesota Department of Natural Resources (MnDNR), Division of Land and Minerals Report “Results from Chemical Analyses and Mineralogical Investigations of Heavy Mineral Concentrate Samples Collected from Glaciofluvial Sediments in Minnesota – Report 284,” published 1991. Each folder in the zip file contains data from the report in a different format. The data is presented in its original file format, a Microsoft Access database, dBase IV files, and an ArcGIS File Geodatabase. Geospatial information for each sample site was taken from the ‘sitedata’ table in the UTMs fields. Additional information about the original data fields can be found in the report listed above. The data is designed to be used as a supplement to the report and plates.

For more information:

Dennis Martin
500 Lafayette Road
St. Paul, Minnesota 55155-4045
tel. (651) 259-5405
fax (651) 296-5939dennis.martin@state.mn.usDisclaimer and Copyright Protection: Maps, Reports, Data, and Other Information - The State of Minnesota makes no representations or warranties express or implied, with respect to the use of the information contained herein regardless of its format or the means of its transmission. There is no guarantee or representation to the user as to the accuracy, currency, suitability, completeness, usefulness, or reliability of this information for any purpose. The user accepts the information “as is." The State of Minnesota assumes no responsibility for loss or damage incurred as a result of any user’s reliance on this information. All maps, reports, data, and other information contained herein are protected by copyright. Permission is granted to copy and use the materials herein for any lawful noncommercial purpose. Any user of this information agrees not to transmit or provide access to all or any part of this information to another party unless the user shall include with the information a copy of this disclaimer.